1. Field of the Invention
This invention relates to an auxiliary battery for portable devices, and more particularly, to an auxiliary battery that can be used for a variety of applications with high electric capacity.
2. Description of the Related Art
Because of the rapid growth of portable devices, a large number of secondary batteries are produced such as lithium ion batteries as internal power sources. Since there are many different types of portable devices, such as notebook PCs (personal computers), cellular phones, audio/video devices and the like, battery voltages in such devices are sometimes different from one another.
Further, because of high demand for such batteries implemented in portable devices to be small and lightweight, batteries suffer from limitation of the size. Therefore, it is difficult to produce a battery with a sufficient length of operating time that can satisfy consumers. Therefore, some device makers produce high capacity batteries that are specific to a particular type of portable devices to fulfill the insufficiency of the power capacity.
On the other hand, a general purpose auxiliary battery that is able to output different voltages is also available in the market. Such an auxiliary battery has voltage terminals for different voltages so as to be used for portable devices with different operating voltages.
However, because the high capacity battery noted above is specifically made for particular portable devices, it can not be used on different types of portable devices. Therefore, it is necessary to prepare specialized batteries and a battery charger for each portable device.
The general purpose auxiliary battery noted above can be implemented on portable devices that have different operating voltages. However, there are various performance limitations in such auxiliary batteries such as not being able to use the portable device while charging the battery, or multiple voltage output terminals cannot be used at the same time. Therefore, the conventional batteries are not convenient enough for present day portable devices.
It is, therefore, an object of the present invention to provide an auxiliary battery for portable devices that can solve the problems involved in the conventional batteries.
It is another object of the present invention to provide an auxiliary battery that is capable of charging the electric power therein while operating a portable device.
It is a further object of the present invention to provide an auxiliary battery which is capable of monitoring the modes of power input to the auxiliary battery and selectively providing the output electric power to the portable device from an external power source such as commercial AC power source or from the inner secondary batteries in the auxiliary battery.
To achieve the above objectives, one aspect of the auxiliary battery of the present invention for portable devices is comprised of a power input section for receiving electric power either from an external direct current power source or a direct current power source converted from an external alternating current power source, a power storage section having a secondary battery for receiving a charge current from the power input section, a power output section having one or more output terminals determined by power requirements of portable devices for producing electric power at the output terminals, and an input power switch circuit for selectively inputting electric power to the power output section either from the power input section when the electric power is available therefrom or from the power storage section when the electric power is unavailable from the power input section.
In another aspect of the present invention, the auxiliary battery for portable devices further includes an output power switch for outputting electric power to the output power section while supplying surplus power to the power storage section for charging the secondary battery.
In a further aspect of the present invention, the auxiliary battery for portable devices further includes a protection circuit for protecting the secondary battery by terminating a charge or discharge operation or disconnecting a charge or discharge circuit when abnormal voltage and/or temperature is detected in the secondary battery.
In a further aspect of the present invention, the auxiliary battery for portable devices further includes an output control circuit for producing a plurality of power outputs at the output terminals at the power output section with voltages different from one another.
In a further aspect of the present invention, the auxiliary battery for portable devices further includes an indicator for showing a remaining level of power in the secondary battery.
According to the present invention, the auxiliary battery ordinarily provides the DC power produced from the external DC or AC power source to the portable device. When the supply of power from the external source is unavailable, the auxiliary battery can provide the power required for the portable device from the secondary battery. When the power from the external source is supplied to the portable device, the auxiliary battery is able to charge the secondary battery with use of the surplus power.
The auxiliary battery is able to protect the secondary battery by terminating a charge or discharge operation or disconnecting a charge or discharge circuit when abnormal voltage and/or temperature is detected in the secondary battery. Further, auxiliary battery of the present invention produces a plurality of power outputs with different voltages. The auxiliary battery is able to show the remaining level of power in the secondary battery.